Benchmark: new Array() vs Array.from()

Script Preparation code:

var randomArray = Array.from({ length: 1000 }, () => Math.floor(Math.random() * 256))
var randomArrayBuffer = new Uint8Array(randomArray)

Tests:

new Array()
new Array(...randomArray)
Array.from()
Array.from(randomArray)
new Array() with ArrayBuffer
new Array(...randomArrayBuffer)
Array.from() with ArrayBuffer
Array.from(randomArrayBuffer)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Array()
Array.from()
new Array() with ArrayBuffer
Array.from() with ArrayBuffer

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/108.0.0.0 Safari/537.36 Edg/108.0.1462.76

Browser/OS: Chrome 108 on Windows

View result in a separate tab

Test name	Executions per second
new Array()	498119.8 Ops/sec
Array.from()	1134377.1 Ops/sec
new Array() with ArrayBuffer	40901.4 Ops/sec
Array.from() with ArrayBuffer	69613.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its test cases.

**Benchmark Definition:**
The benchmark tests different methods of creating an array in JavaScript, specifically comparing `Array.from()` with `new Array()` and variations that use a random ArrayBuffer as input.

**Options Compared:**

1. **`Array.from(randomArray)`**: This method creates a new array by mapping over the `randomArray` and using `undefined` as the initial value.
2. **`new Array(...randomArray)`**: This method creates a new array by spreading the elements of `randomArray`.
3. **`new Array(...randomArrayBuffer)`**: This method creates a new array by spreading the elements of `randomArrayBuffer`.

**Pros and Cons:**

* **`Array.from()`**:
	+ Pros: More concise, readable, and expressive syntax.
	+ Cons: May have performance overhead due to the mapping operation.
* **`new Array(...)`**:
	+ Pros: Lightweight, fast, and suitable for large arrays.
	+ Cons: Less readable and explicit than `Array.from()`, can lead to errors if not used carefully.

**Using a Random ArrayBuffer:**

The test case uses a random ArrayBuffer as input to simulate a more realistic scenario. This allows the benchmark to measure performance in different contexts, such as when working with large arrays or arrays generated from external data sources.

**Library and Purpose:**
In this benchmark, `Array.from()` is used as a library function to create an array from a given iterable (in this case, a random array). The purpose of using `Array.from()` is to test its performance compared to other methods.

**Special JS Feature/Syntax:**
There are no special JavaScript features or syntaxes mentioned in the benchmark definition. However, it's worth noting that `Array.from()` was introduced in ECMAScript 2015 (ES6), and the benchmark may be using a version of JavaScript that supports this feature.

**Other Alternatives:**

* **Using `new Uint8Array(...)`**: Instead of creating an array from a random ArrayBuffer, the test case could use `new Uint8Array()` to create a typed array. This would allow testing performance with a specific type of array.
* **Using other array creation methods**: The benchmark could be extended to include other array creation methods, such as using `Array.prototype.push()` or `Array.prototype.fill()`, to provide more comprehensive results.

Overall, the benchmark provides a useful test case for measuring performance differences between various array creation methods in JavaScript.

Related benchmarks:

new Array() vs Array.from() (version: 3)

Test Array creation methods on a random ArrayBuffer

Comparing performance of: new Array() vs Array.from() vs new Array() with ArrayBuffer vs Array.from() with ArrayBuffer

Created: one year ago by: Registered User

Jump to the latest result

new Array()

Array.from()

new Array() with ArrayBuffer

Array.from() with ArrayBuffer

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):